thyroid cancer

Radioactive iodine treatment

Radioactive iodine can be used as a radiation treatment for thyroid cancer, since the thyroid gland in particular takes up iodine in the body. The cancer cells take up radioactive iodine (called iodine–131) which causes the cancer cells to die. It is usually given to destroy remaining thyroid cells, not removed by surgery and any that may have spread.

Radioactive iodine treatment is an option for people with the papillary and follicular types of thyroid cancer and often starts at least 4-5 weeks after surgery.

For women who are pregnant and those who are breastfeeding, radioactive iodine treatment is not suitable. Your doctor will recommend stopping radioactive iodine treatment, before starting treatment.

Guide for people considering radioactive iodine treatment

Preparing for radioactive treatment

For about 2 weeks before treatment, you will need to avoid foods high in iodine such as seafood, iodised salt, some dairy food and any food coloured pink with the additive E127. You need to have a low iodine diet because too much iodine in your body can stop the treatment working well. Your cancer care team will provide you with advice on foods to avoid.

You will need to either stop taking thyroid hormone replacement pills temporarily, or have injections of thyroid stimulating hormone (Thyrogen) while taking the hormone replacement. This is to increase the thyroid stimulating hormone in your body, and your cancer care team will discuss the best option available for you.

If you have the option of stopping thyroid hormone replacement during the preparation, there may be some side effects due to hypothyroidism such as tiredness.

After radioactive iodine treatment

After the radioactive iodine treatment, you will have a full body radioisotope scan using a small amount of radioactive liquid. The scan can help detect if any cancer cells are left or if the cancer has spread. The scan is painless and causes few side effects, and you will not be radioactive after the scan.

At home you may need to continue safety measures such as sleeping alone, washing your clothes separately and preparing your own food. You may be advised to sit to pass urine, shut the lid and flush the toilet several times.

You may be advised to take precautions to avoid pregnancy for a while after treatment, If you or your partner want to have a baby after radioactive iodine treatment, you should talk to your doctor for advice about suitable timing.